GPS-based positioning and navigation methods have been demonstrated to be effective for mobile device applications. Still, there are some challenges to apply the same approach to the indoor environment, which may be primarily due to the significantly degraded or unreliable GPS signals received inside of buildings.
Conventional approaches to indoor navigation may use a mobile device's embedded sensors, such as an accelerometer, gyro, magnetometer, etc. While efforts may have improved the sensors' hardware and developed algorithms for sensors data filtering, sensors-based dead reckoning may provide relatively accurate navigation for only a short period of time (usually less than a few minutes).
In general, dead reckoning (DR) may involve calculating one's current position by using a previously determined position (or fix), and advancing that position based upon estimated/known course and estimated/known speed over elapsed time. However, dead reckoning is subject to cumulative errors. As dead reckoning is running for a long interval, errors may accumulate that derive from gyro drift, magnetometer inference, a mix of user moving acceleration with gravity acceleration, and/or other types of sensor-based errors. The present embodiments may, inter alia, overcome these and other deficiencies.